GATT timeout when reading a characteristic when notify enabled

RE: GATT timeout when reading a characteristic when notify enabled

RVM — Sat, 23 Jan 2021 01:58:27 GMT

Just wondering if you could help me understand how/why adding an event handler for a 'missing attribute' solves the problem you see when 'reading an existing characteristic'?

Cheers

RMV

RE: GATT timeout when reading a characteristic when notify enabled

Nick_RA — Tue, 25 Aug 2020 10:22:48 GMT

No, the characteristics were all fine. I didn't bother wasting time with a DK because logic dictates it couldn't be related to hardware.

After some hours going through my code and comparing it to the Blinky example I found that I did not have a BLE handler for BLE_GATTS_EVT_SYS_ATTR_MISSING. Added this and it now works.

RE: GATT timeout when reading a characteristic when notify enabled

Mttrinh — Tue, 18 Aug 2020 12:43:12 GMT

Hi,

Sorry for the late reply,

Have you had any progress with this issue? It would be good to try it on a DK as well just to be sure.

But I agree that it probably is something wrong with the configuration of the characteristic. I suggest you go through this and see that everything is set up correctly.

RE: GATT timeout when reading a characteristic when notify enabled

Nick_RA — Thu, 06 Aug 2020 15:25:49 GMT

OK let me clarify my setup:

Yes this is a custom board. I haven't tried my code on a DK but there shouldn't be any difference to the BLE side, just the I/O. Also, the blinky example runs just fine on my custom board so I'd expect the same set of results running my code on the DK.

I do also have 2 x PCA10040 DK boards. One is set up to work with NRF Connect, the other is set up for the Wireshark sniffer.

It's definitely because there's something screwy with the Client Characteristic Configuration because it's returning an "unknown handle" . Is that set up as part of the characteristic add process? I can't see anything in the Blinky code that does anything like that.

Edit: Sorry forgot to add the only mods to the code above is i) I removed the debug lines for clarity and ii) I just changed the name to "mysvc" as this is a public forum.

RE: GATT timeout when reading a characteristic when notify enabled

Mttrinh — Thu, 06 Aug 2020 13:46:59 GMT

What other modifications have you done to the code except for the one mention above?

[quote user=""]PCA10040 DK to debug my nRF52832 product.[/quote]

Are you using a custom board? Have you tested with a DK?

[quote user="Nick_RA"]Here's a Wireshark trace which may be of some helpgatt timeout.pcapng[/quote]

I will have a look.

RE: GATT timeout when reading a characteristic when notify enabled

Nick_RA — Wed, 05 Aug 2020 15:23:34 GMT

Hi thanks for replying. No, nothing gets thrown up during debug, also I can confirm that I checked err_code after the function calls above and they return zero (success).

Here's a Wireshark trace which may be of some helpdevzone.nordicsemi.com/.../gatt-timeout.pcapng

RE: GATT timeout when reading a characteristic when notify enabled

Mttrinh — Wed, 05 Aug 2020 13:45:57 GMT

Hi,

Can you try to debug your application and see if you get any error codes when this happens?